Middleweight boxing superstar Saul 'Canelo' Alvarez has beaten rival Gennady 'GGG' Golovkin in a rematch to win the WBA Super and WBC world titles and hand the Kazakhstan fighter the first and only loss of his professional career.

Mexican Alvarez won by scores of 115-113, 115-113 with one judge scoring a draw 114-114 to record a majority decision against the undefeated Golovkin in a re-run of their first fight one year ago, which ended as a draw.

The fight threatened to be a chess match from the off, with both fighters feeling each other out in the first couple of rounds at the T-Mobile Arena in Las Vegas on Saturday.

For Golovkin, the fight seemed to be centered on his trademark stiff jab, while Canelo appeared the more active of the two boxers, ripping shots to his opponent's body with great effect.

The fight was evenly poised through the middle rounds, Golovkin, aged 36 and perceived by many to be in the early twilight stage of his career, sticking behind his commanding jab, while Canelo continued to hack away at the body with tremendous results.

Golovkin offered back huge shots of his own that at times looked to stop the younger man in his tracks, but the champion looked exhausted from the punishment to his midriff, if not a little shopworn and unable to withstand such onslaughts with the resilience he showed in the previous fight.

Both fighters were cut in the course of the bout, Canelo sporting a long laceration underneath his left eyebrow, with Golovkin cut around the right eye and with swelling to his high cheekbones.

In the championship rounds, the two fighters came alive and a tenth round was punctuated by numerous defiant Golovkin shots to the head that seemed to have Canelo rocked and sway the action in favor of the older man.

This carried on much the same in rounds eleven and twelve, with Canelo showing a granite chin to stand up to a hailstorm of Golovkin power shots.

The fight ended with vicious uppercuts and long, reaching hooks from both fighters, and then an embrace, each man drained from the pain dished out to each other.

In the end, Canelo clinched the belts and handed Golovkin the first loss of his professional career with a majority decision victory. Many observers believed there was no room for argument for the bout going either way, but, in the end, the judges favored the youthful aggression of Canelo to the calculated experience of the masterful, but now defeated Golovkin.